The invention relates to a process for controlling an internal combustion engine.
In practice, large diesel engines are delivered without automatic valve clearance compensation. After a fixed, predetermined period of operation, therefore, the valve clearance must be adjusted by a service mechanic according to a maintenance plan. The maintenance plan lists the boundary conditions such as an engine cooling water temperature of less than 40° C. and each of the individual steps. First, an engine-cranking device is attached; the cylinder head covers are removed; and the cranking device is used to close the reciprocating gas valves one after the other. In the closed state, a feeler gauge is then used to check the actual valve clearance of each valve. If this deviates from the nominal valve clearance, the service mechanic must adjust the actual valve clearance with an adjusting screw until the actual value clearance agrees with the nominal valve clearance. In the case of a large diesel engine with sixteen valves, for example, this is a time-consuming and cost-intensive procedure and, if the engine is installed in a ship, it leads to correspondingly high harbor docking fees.
A measure for improving this situation consists in measuring the actual position of the reciprocating gas valve inductively or capacitively (DE 198 30 667 A1) by way of a normally open contact (DE 196 52 719 A1) and to use this as a basis for the further control of the internal combustion engine, such as a variable valve control. It is known from WO 2005/064281 A1 that the actual position of a component capable of linear movement can be measured by magnetic coding, that this position can be compared with a calibrated zero position, and that a positional deviation can be determined from that. The critical point in these devices and methods is that, although the temperature-caused change in length of the reciprocating gas valve is in fact detected as a positional deviation, it cannot be interpreted as allowable or not allowable in the sense of wear. A clear conclusion with respect to operational reliability therefore cannot be reached.